1. Field of the Invention
The present invention relates to a GPS device, and more particularly to a power saving device for a GPS device.
2. Description of Related Art
The upgrading of the manufacturing technology and the functions of an electronic product enable the use of a GPS device to be more popular. There are many types of the GPS device such as a portable GPS device convenient for being used in an individual's mountain climbing and travel, GPS device combined with a cellular phone and GPS device combined with a vehicle allowing a user to realize his position and the direction of the destination that he wants to go if it is operated in coordination with an electronic map.
All general portable GPS devices use a battery to provide electricity. When a GPS receiver is in a normal operation, it is very power consuming. If the GPS device is not moved, it can enter a rather power consuming mode, the power can then be saved so that the use life of the battery can be extended.
U.S. Pat. No. 6,774,838 discloses a power saving device and method for a GPS receiver, in which the power saving device allows the GPS receiver to be connected to an oscillation switch and the vibration generated from the moving of the GPS receiver can be utilized to actuate the oscillation switch to turn on the power of the GPS receiver automatically with a power controller. The oscillation switch enables the power controller to turn off the power of the GPS receiver automatically when the GPS receiver is not moved so that the power can be saved.
An acceleration of gravity sensor (G-sensor) is installed in a several GPS devices. The G-sensor detects the variation of gravity to measure the acceleration generated from the movement of a body and output a simulated voltage signal. This can provide the data of the acceleration of the body so as to assist the GPS receiver to provide the data of the velocity and the position of the body even in such as a time period that the satellite signals cannot be received or well received when it is in tunnel or is blocked by mountains, trees, buildings and etc. When the G-sensor is under a work voltage of 3.3 volts, the power consumption thereof is 1 mA; this is far less than the one needed for the GPS receiver.